Context: the studies of the last decades pointed that vitamin D is an important player in reproduction, most of the evidence coming from animal and experimental studies. However, data in humans provided by clinical studies are controversial, in particular studies from in vitro fertilization (IVF) offering divergent results. Objective of the study was to analyze the relationship of serum levels of 25hydoxyvitamin D and reproductive outcome in IVF. Material and patientss: we performed a retrospective study which included 153 female patients with all cause infertility who underwent IVF between October 2015 and June 2017 in a private fertility clinic. Interventions: none Main outcome measures: the following data were retrieved from the medical records: age, anti-mullerian hormone (AMH), 25hydroxyvitamin D, number of oocytes retrieved, number of embryos obtained, number of good quality embryos, the presence of clinical pregnancy. Results: the study group had a mean age of 34.5±4.34 years, a mean AMH value of 3.58±3.19 ng/mL and a mean level of 25hydroxyvitamin D of 21±8.21 ng/mL. Fifty % of patients had 25hydroxyvitamin D below 20 ng/mL (deficiency), 39.8 % had 25hydroxyvitamin D between 20 and 30 ng/mL (insufficiency) and 9.8 % had 25hydroxyvitamin D above 30 ng/mL (sufficient). In a multivariate linear regression model serum level of 25hydroxyvitamin D was significantly correlated with oocytes and embryos number after adjustment for age and AMH. However, the number of good quality embryos and pregnancies were similar in the three groups of patients according to 25hydroxyvitamin D serum level. Conclusions: serum level of 25hydroxyvitamin D is positively associated with oocytes and embryos number in in vitro fertilization.